FIELD OF THE INVENTION
The present invention relates generally to a system for inhibiting or limiting the transfer and propagation of cracks from foundational materials or substrates, such as subflooring, to finish layers disposed thereon, such as tile, stone and other relatively brittle materials. In particular, the invention relates to an innovative system incorporating a composite material disposed between the substrate and the finish layers to absorb or dissipate movement in the substrate due, for example, to cracking, fissuring and the like.
A number of surface finishing techniques are known for covering floors, walls, counters and the like. One such technique involves securing tile, stone panels or sheets and the like to the support surface or substrate via a cement or glue. In the case of flooring, such surface finishing materials are generally cemented to a subfloor or foundation layer such as concrete. The subfloor may be a slab disposed directly on the ground, or may consist of a single or multiple sections supported on a superstructure creating elevated floor levels, such as in a multistory structure.
Where tiles, stone and similar materials are applied to concrete and similar substrates, a problem exists when the substrate undergoes movement, cracks or fissures beneath the overlying material. This problem is exacerbated by the generally brittle nature of many finishing materials, such as tiles and stone. Where such materials are cemented or glued directly to the substrate, cracks in the underlying layers tend to be transmitted to the finishing materials, resulting visible cracks. In the case of sectional finishing materials, such as ceramic tile, such cracks may occur both between tiles and through individual tiles. Over time, such cracking can substantially mar the appearance of the finished surface and deteriorate the surface, particularly surrounding the broken or fractured areas.
Techniques have been developed in an attempt to prevent, or at least to inhibit, the propagation of cracks from a structural substrate to an overlying finishing material. In one such technique, a non-woven fabric sheet is laid over and secured to the substrate and the finishing material is secured to the fabric. In a similar technique, a polymer membrane layer is disposed over the substrate and the finishing material secured to the membrane. A serious drawback of both of these known techniques is the relatively high cost of the intermediate sheet or membrane, which significantly increases the cost of the overall finishing operation. Moreover, certain formulations of the intermediate sheets or membranes do not provide the resiliency desirable for suppression or inhibition of crack transmission to the finishing material.
Other, generally similar, techniques have been proposed for interposing various materials between a subfloor and a finishing material, such as tile or stone, to absorb or dissipate sound. In one such technique, a relatively thick layer of composition cork, typically 6 millimeters thick, is interposed between the substrate and the finishing material. The material aids in deadening sound through the flooring, but typically only provides limited capability for suppressing crack transmission between the subfloor and finishing layer. Moreover, like the non-woven and polymer membrane materials, the composition cork material can add unnecessarily to the cost of the finishing operation, particularly where sound deadening is less an issue than crack inhibition.
There is a need, therefore, for an improved technique for isolating a finishing layer, such as a relatively brittle floor covering, from a structural substrate so as to prevent or inhibit transmission of cracks and fissures from the substrate to the finishing layer. In particular, there is a need for such a technique that makes use of an isolation material that is less expensive than known materials, but that is sufficiently resilient to isolate the substrate from the finishing layer. In addition, the technique should be relatively easy and rapid, so as to permit the finishing operation to be carried out in a timely manner by artisans already familiar with the basic finishing technique.